Orthodontic onlay for light-wire technique

ABSTRACT

An orthodontic onlay for use with a single arch wire in a lightwire technique. The onlay is an integral plastic member for direct cementing to a tooth. It has a curved base portion whose rear surface conforms to the cheek surface of a tooth and has a series of cement-holding openings leading therefrom. The front surface of this base portion provides a bracket portion having a snap-in notch with a narrow, generally circular seat for an arch wire. An entrance portion of the notch is formed by a pair of facing walls resilient enough so that while the entrance opening is normally substantially smaller in diameter than the arch wire, its walls spread apart when the arch wire is pressed against them, to admit the arch wire to the seat, and the walls then spring back to lock the arch wire in the seat. The onlay also has one or more vertical openings for anchoring control auxiliaries. In one form, notches adjacent the top and bottom of each opening enables tying ligature wires for additional control.

. [63] Continuation-in-part of Ser. No. 193,400, Oct. 28

United States Patent [1 1 Northcutt ORTHODONTIC ONLAY FOR LIGHT-WIRETECHNIQUE [76] Inventor: Michael E. Northcutt, 12720 Dianna Dr., LosAltos Hills, Calif. 94021 [22] Filed: July 31, 1972 [21] Appl. No.:276,715

Related US. Application Data Primary Examiner-Robert Peshock Attorney-W.E. Schuyler, Jr. et al.

[ Oct. 16, 1973 [5 7 ABSTRACT An orthodontic onlay for use with a singlearch wire in a light-wire technique. The onlay is an integral plasticmember for direct cementing to a tooth. It has a curved base portionwhose rear surface conforms to the cheek surface of a tooth and has aseries of cement-ho1ding openings leading therefrom. The front surfaceof this base portion provides a bracket. portion having a snap-in notchwith a narrow, generally circular seat for an arch wire. An entranceportion of the notch is formed by a pair of facing walls resilientenough so that while the entrance opening is normally substantiallysmaller in diameter than the arch wire, its walls spread apart when thearch wire is pressed against them, to admit the arch wire to the seat,and the walls then spring back to lock the arch wire in the seat. Theonlay also has one or more vertical openings for anchoring controlauxiliaries. In one form, notches adjacent the top and bottom of eachopening enables tying ligature wires for additional control.

18 Claims, 12 Drawing Figures PATENTEUUBT 1 BIHH 3.765.091

SHEET H]? 3 PAIENIEMEHBI H $765,091

- snznaur FiG ORTHODONTIC ONLAY FOR LIGHT-WIRE TECHNIQUE CROSS-REFERENCETO RELATED APPLICATIONS This application is a continuation-in-part ofapplication Ser. No. 193,400 filed Oct. 28, 1971.

BACKGROUND OF THE INVENTION This invention relates to orthodontic onlaysfor use in the lightwire orthodontic technique. This onlay ischaracterized by (1) being rigid plastic attached directly to the toothinstead of being secured to a band, (2) the light arch wire beingattached by a snap-in to a narrow, substantially point-contact circularoversize seat, so that no pins are used, and so that there is no bindingat the seat, (3) integral provisions for the mounting of controlauxiliaries, and (4) superior and inferior wings enabling tying ofligature wires, etc.

The light-wire technique has been known for some time, for example, seeKessling U.S. Pat. No. 2,915,824 and Begg U.S.. Pat.'Nos. 3,128,553 and3,163,933. In this technique a single light, round arch wire is used.Less force is exerted on the tooth than in the older technique using aheavy square or round arch wire. it has been found possible to obtainresults that are just as effective as, sometimes even more effectivethan, those obtained with heavy wires, and to do so with less discomfortto the user and better overall development.

The use of a light arch wire provides for a more resilient system thando the heavier arch wires, which are typically rectangular. In additionthere is less friction between a round wire and an orthodontic bracketthan with a rectangular wire, so that there can be much greater ease ofmovement of the teeth. In rectangular arch wire systems (e.g., see theAngle US. Pat. No. 1,553,797), constant binding occurs, and this resultsin much pain to the patient. By using a light arch wire, lighter forcesof greater resilience can be applied and can act over a longer period oftime. From a treatment standpoint, this enables treatments to be spacedabout 6 weeks apart instead of having to be spaced only about 3 weeksapart.

Heretofore, the light-wire technique has generally been practicedexclusively with the use of bands and metal brackets secured to thebands. The bands themselves are well known to be uncomfortable, and theattachment of the light-wire heretofore has generally been accomplished(as in the Begg technique) by means of a pin. Recently some plasticbrackets have been provided for direct cementation to the tooth, but thepinning technique is still used. Although these systems are operative,there has been a notable lack of control, and eventually the pin has tobe replaced with various springs and auxiliaries. Every time the archwire is pulled out, which happens about every 6 weeks, the orthodontistmust pull all the pins and then repin the members. This quite laboriousfor each installation, and thereby may be numerous changes of the archwire during treatment.

The pins which have been used are each a separate member and they mustbe continually inventoried, repurchased, and used. Pinning also has amarked disadvantage in that the pins trap food particles and ofteninfringe on the patients gum tissue. Worst of all, perhaps, the pinstake a considerable amount oftime to place into the small slotsavailable on prior-art brackets.

Some patents (including Wallshein U.S. Pat. Nos. 3,052,027 and 3,052,028and Brader U.S. Pat. No. 3,327,393) have shown snap-in brackets, all ofthem metal except for Wallshein U.S. Pat. No. 3,052,027, which uses ahollow-rubber dome that has undesirable resiliency and give. All ofthese result in binding of the arch wire, preventing free adjustment,and all resulting in undesirable bracket forms.

It is most desirable to have a system which retains the use of lightwires but at the same time avoids superfluous and time-consumingconnecting procedures, whether by ligation in the edgewise technique orby pinning in the Begg technique. The present invention seeks toaccomplish this. For example, it reduces the time required to secure anarch wire from about ten minutes to about one minute.

Among the objects of the present invention are to provide a techniquewhich enables quicker installation and quicker removal, and whichenables a more rapid change from one arch wire to another. Anotherobject of the invention is to provide a less complicated and lessexpensive arrangement for practicing the light-wire technique, in whichno pins are required and the light wire is snapped into the brackets.

An other object of the invention is to provide the patient with a morecomfortable arrangement for practicing the light-wire technique,obviating the use of bands.

Another object of the invention is to improve greatly the estheticeffect. Clear plastic brackets or onlays can be nearly invisible from afew feet away and can thereby replace the tin grin common today.

Another object of the invention is to provide a technique in whichauxiliaries are readily used in conjunction with the light-wiretechnique for uprighting which means, basically, holding the tip of thetooth and bringing the root back.

Another object of the invention is to provide a system for thelight-wire technique which at the same time enables the use of ligatureties where necessary.

SUMMARY OF THE INVENTION This invention comprises an orthodontic onlayfor use with a single arch wire in the light-wire technique. This onlayis an integral plastic member and is directly cemented to a tooth. Itcan be the same color as the tooth or can be clear. A curved baseportion has a rear surface that conforms to the forward surface of thetooth and a series of cement-holding openings leading therefrom. Itsfront surface provides a bracket portion having a wire-receiving slotgiving access to a generally circular seat for an arch wire. Thediameter of the circle is slightly greater than the diameter of the archwire, enough so to allow to a round wire some freedom of movement whichprevents frictional binding. The entrance portion lies between a pair ofthin walls, which are resilient enough so that the entrance portion isnormally substantially narrower than the diameter of the arch wire, andthe arch wire is inserted by being snapped in: the two walls are forcedapart to admit the arch wire to the seat and then spring back to lockthe arch wire in the seat. No pinning is required, so that theinstallation time is much quicker, and changing from one arch wire toanother takes only a few minutes. The arch wire can readily be bent asdesired to produce the desired effects.

The onlay also comprises one or more openings for anchoring a controlauxiliary. In one form of the invention, there is a single centralvertical through opening of substantial length for this purpose, whilein another form of the invention there are two spaced-apart openings,also extending vertically and for the same basic purpose. These circularcolumnar openings are preferably about 0.020 inches in diameter toreceive the currently used uprighting springs, which are about 0.014inches in diameter.

Other objects and advantages of the invention will appear from thefollowing description of some preferred embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a greatly enlarged view in perspective of a dental onlayembodying the principles of the invention.

FIG. 2 is a fragmentary view in section taken along the line 22 in FIG.1 and also showing a portion of the tooth to which the onlay of FIG. 1is attached by cement.

FIG. 3 is an enlarged view in side elevation of the notch through and inwhich the arch wire is snapped in.

FIG. 4 is a view similar to FIG. 3 showing another form of snap-innotch.

FIG. 5 is a view in perspective of a modified form of an orthodonticonlay embodying the principles of the invention and having two verticalopenings for receiving control auxiliaries.

FIG. 6 is a view in section taken along the line 66 in FIG. 5.

FIG. 7 is an occlusal view of an installed orthodontic system using theonlay of FIG. 5.

FIG. 8 is an enlarged fragmentary view in elevation of a portion of thesystem of FIG. 7.

FIG. 9 is a view similar to FIG. 8 showing the use of two auxiliariesfor uprighting.

FIG. 10 is a view in front elevation of another modified form of onlayembodying the principles of the invention.

FIG. 11 is a view in side elevation of the onlay of FIG. 10, partlybroken away and shown in section.

FIG. 12 is a top plan view of the onlay of FIGS. 10 and 11.

DESCRIPTION OF PREFERRED EMBODIMENTS THE ONLAY OF FIGS. 1-4

FIG. 1 shows in perspective an enlarged view of an orthodontic onlay l0embodying the principles of the invention. The onlay 10 is an integralplastic member made of such plastic as methyl methacrylate, polystyrene,polycarbonate, polypropylene, polyvinyl fluoride, polyethylene, nylon,tetrafluoroethylene, or other suitably strong material. The plastic maybe clear or may be tooth color and it should be substantially rigid, notgiving to the force of the arch wire. It has a base portion 11 and abracket portion 12. The base portion 11 has a rear surface 13 which iscurved to conform to the curve of the front surface 14 ofa tooth 15 towhich the onlay 10 is affixed. When the tooth l5 hasa double curve, therear surface 13 of the base portion 11 of the onlay 10 has a doublecurve, too. The base portion 11 is also provided with a series ofopenings 16 leading from the rear surface 13 to help to retain and bondto a suitable cement 17. These openings 16 may be blind openings orrecesses, but in FIGS. 1 and 2 they are shown as through openings. Asuitable epoxy type cement 17 may be used, so long as it is non-toxic.Also, the surface 13 may be given a plasma treatment, as described in myco-pending application Ser. No. 250,959, filed May 8, 1972, to provide athin surface portion 18 that enhances adhesion of the cement 17 oftengiving more than 10 times the adhesion of the same material untreated.This is not a coating but a treatment that rearranges the molecularstructure of the surface portion.

The forward surface 19 of the base portion 11 may be parallel to therear surface 13 or may be flat. In any event, the bracket portion 12 isintegral with it and is constructed to hold the light arch wire securelyat a constant distance away from the tooth 15, the arch wire later beingbent as desired to produce corrective forces. The bracket portion 12projects out from the base portion 11 and as shown, reinforcement may beprovided by a relatively bulky upper portion 20 and a relatively bulkylower portion 21 between which lie a thinner tapered central portion 22which is narrow where it meets the arch wire attachment for the sake ofaccuracy, and yet receives strength from the supporting members 20 and21.

A notch 23 is provided for receiving the arch wire, which is snappedinto a central circular seat 24 (see FIGS. 3 and 4) that preferablyholds the arch wire fairly loosely in substantially a point contact.This point contact and the sizing of the seat 24 to be slightly largerin diameter than the arch wire greatly reduces binding. For example, an0.018 inches arch wire is characteristically placed in a seat 24 havinga diameter of 0.023 inches and width of 0.020 inches. The narrow widthgives substantially point contact and the oversize diameter affords somefreedom for the tooth to settle without binding. Access to the circularseat 24 is provided by an entrance opening 25, which in this example,may be 0.012 inches wide. Thus an upper wall 26 and a lower wall 27 arespaced apart from each other by a distance less than the diameter of thearch wire, and they are forced apart when the arch wire is pressedagainst them; then they snap back into place. They can thus yieldresiliently even though made of rigid material. As shown in FIG. 3, thisentrance opening 25 may have tapered edges 28 and 29 that lead in to asharp vertex 30 or, as shown in FIG. 4, the notch may be somewhatdeeper, and have outer splayed corners 31 and 32 leading to parallelwalls 33 and 34, which may be somewhat wider apart than the narrowestportion of the FIG. 3 notch, but which are still closer together thanthe diameter of the arch wire and are resilient enough to move apart andthen snap back upon the arch wire to hold it firmly in place.

The bracket portion 12 also is provided with a vertical through opening35 of substantial length, open at each end to leave an open tube. Asshown in FIGS. 1 and 2 this is a single cylindrical opening 35 thatextends from top to bottom of a downwardly recessed portion 36 of theportion 12. This opening 35 can hold a control auxiliary, such as aspring member that is used in uprighting.

In use, the orthodontist cements each onlay 10 to a tooth, and when allthe onlays 10 are in place he then snaps the arch wire in place. Theends of the arch wires may be held by conventional molar tubes (Cf. FIG.7) and exert the desired force on the teeth. Auxiliaries are insertedwhere needed for uprighting or for such other uses as are desired.

The cement 17 holds the onlay l0 firmly to the tooth, and yet the onlaysare easily removed with a suitable tool, described in another pendingapplication of mine.

THE ORTHODONTIC ONLAY OF FIGS. 5-9

FIGS. 5-9 show a modified form of dental onlay having many similaritiesto that already described. Here again, there is a base portion 51 and abracket portion 52. The base portion 51 is again provided with a rearsurface 53 that fits the front surface 54 of the tooth 55. The rearsurface 53 in this instance is shown with parallel recesses 56 (FIG. 6),shaped like the dove-tails used in carpentry, for providing theengagement by the cement. This is another illustration of a way to havethe surface provide extra hold for the cement. A plasma-treated portion57 is again provided to enhance bond.

The bracket portion 52 is provided with bulkier upper and lower members60 and 61 having curved ends 63 for comfort, and a snap-in notch 64 isprovided for holding the arch wire. The notch 64 is basically the sameas the notch 23 described in the onlay 10 of FIGS. 14.

The basic difference between the onlay 50 and the onlay 10 is that theonlay 50 has two vertical through openings 65 and 66, one at each end ofthe bracket portion 52 and again at the rear thereof behind the archwire.

FIGS. 7 and 8 illustrate an installation of the device of FIG. 5, FIG. 7being an occlusal view and showing molar tubes at each end by which anarch wire 71 is secured. FIG. 7 shows the path of the arch wire 71 as itgoes across a series of onlays 50, each embodying the principles of theinvention, and each being like that of FIG. 5, though with somewhatdifferent shape for each type of tooth. Substantially the same viewcould be used to represent the device of FIG. 1, except that there wouldbe only one through opening 35, instead of the two openings 65 and 66shown. FIG. 8 shows that the wire 71 is relatively undistorted.

FIG. 9 shows use of auxiliaries 75 and 76, members having one or two orthree coils77 of spring wire, each having a verticalpost 78 whichextends through one of the openings 65 or 66 and then each havinghorizontal portion 79 and another vertical anchor portion 80 whichextends through the opening 65 or 66 of a neighboring onlay 50, as inthe right hand side of FIG. 9, or is anchored to the arch wire 71itself, as on the left side of FIG. 9. Either practice is proper,depending on circumstances.

FIGS. 10-12 show another modified form of plastic onlay whichembodiesthe principles of the invention. Its base portion 101 has a doublycurved rear surface 102, preferably given the plasma treatment. Thereare through openings 103 and blind openings 104 to increase adhesivearea. A bracket portion 105 has tapering surfaces 106 leading to agenerally circular seat 107 at an angle of about 20, and an entrancenotch 108 like that shown in FIG. 4 enables insertion of the arch wire.

The bracket portion 105 has a forward portion 110 and a rear portion 111having a single vertical columnar tubular opening 112. The rear portion111 has upper and lower shelves 113 and 114, and the forward portion isrecessed by upper and lower rectangular notches 115 and 116- extendingdown as far as the shelves and providing thereby two upper Wings 117 and118 and two lower wings 120 and 121. This structure enables tyingligature wires for additional controls, when necessary or desired. Also,the notches 115 and 116 can be used in conjunction with an insertiontool enabling ready positioning on the tooth when adhering it to thetooth.

While this onlay 100 allows great freedom of movement between thetooth-onlay combination and the arch wire, still on each side of thesnap ring 107 the tapered surfaces 106 act as limits, by engaginggreater surface areas with the arch wire if the wire is at an angleequal to or beyond that of the taper. Since the maximum root tip angleof 15 occurs in upper cuspids, tipping much in excess of this wouldrequire a retracing of movement of the teeth. In the present invention,frictional resistance to tipping beyond 20 occurs in any direction, dueto the tapered walls 106 on each side of the ring 107 and frictionbuilds up, applying a brake to excessive tipping. In this regard, thissystem is unique among systems using the light wire technique.

To those skilled in the art to which this invention relates, manychanges in construction and widely differing embodiments andapplications of the invention will suggest themselves without departingfrom the spirit and scope of the invention. The disclosures and thedescription herein are purely illustrative and are not intended to be inany sense limiting.

I claim:

1. An orthodontic onlay for use with an arch wire in a light-wiretechnique comprising a plastic member having a base portion forattachment to a tooth and an outwardly projecting bracket portion with anarrow seat for an arch wire, said bracket portion having a slot definedby a pair of walls for a snap-in entrance to said seat, said wallsdefining a slot narrower than said seat so that they may be forced apartby the wire when a wire is inserted or removed, the horizontal width ofsaid bracket at said slot being substantially greater than the width ofsaid seat.

2. The orthodontic onlay of claim 1 wherein the width of said seat issubstantially the same as the diameter of the wire.

3. The orthodontic onlay of claim I having at least one vertical openingthrough said bracket portion for anchoring a control auxiliary.

4. The orthodontic onlay of claim 3 having a shelf at the top and bottomof said vertical opening and wings on each side of said bracket forwardof said shelf and extending vertically therebeyond and separated fromeach other, for tying ligatures thereto.

5. The orthodontic onlay of claim 1 wherein said slot comprises anouterportion having converging surfaces leading to two parallel surfacesthat lead into said seat.

6. The orthodontic onlay of claim 1 wherein said bracket portionincludes tapered surfaces that converge toward each side of said seat.

7. The orthodontic onlay of claim 6 wherein the surface on each side ofsaid seat slopes away therefrom in all directions at an angle of about20, thereby resulting in imparting a braking force of friction to thearch wire when it enters or leaves the seat in either direction at anangle of the same amount.

8. The orthodontic onlay of claim 1 wherein said bracket portiondiverges laterally from each end of the walls defining said slot.

9. An orthodontic onlay for use with an arch wire in a light-wiretechnique comprising a plastic member to be directly cemented to a toothand having a base portion with a rear surface that conformssubstantially to the forward surface of the tooth to which it is to becemented and a bracket portion with a generally circular narrow seat foran arch wire, said bracket portion having a slot defined by a pair ofwalls for a snap-in entrance to said seat, said walls defining a slotnarrower than said seat so that they may be forced apart by the wirewhen a wire is inserted or removed, the horizontal width of said bracketat said slot being substantially greater than the width of said seat.

10. The orthodontic onlay of claim 9 wherein the width of said seat issubstantially the same as the diameter of the wire.

11. The orthodontic onlay of claim 9 having at least one verticalopening through said bracket portion for anchoring a control auxiliary.

12. The orthodontic onlay of claim 11 having a shelf at the top andbottom of said vertical opening and wings on each side of said bracketforward of said shelf and extending vertically therebeyond and separatedfrom each other, for tying ligatures thereto.

13. The orthodontic onlay of claim 9 wherein said slot comprises anouter portion having converging surfaces leading to two parallelsurfaces that lead into said circular seat.

14. The orthodontic onlay of claim 9 wherein said bracket portionincludes tapered surfaces that converge toward each side of said seat.

15. The orthodontic onlay of claim 14 wherein the surface of each sideof said seat slopes away therefrom in all directions at an angle ofabout 20, thereby resulting in imparting a braking force of friction tothe arch wire when it enters or leaves the seat in either direction atan angle of the same amount.

16. The orthodontic onlay of claim 9 wherein said bracket portiondiverges laterally from each end of the walls defining said slot.

17. The orthodontic onlay of claim 9 wherein said plastic is clearplastic.

18. The orthodontic onlay of claim 9 wherein said plastic is toothcolor.

1. An orthodontic onlay for use with an arch wire in a lightwiretechnique comprising a plastic member having a base portion forattachment to a tooth and an outwardly projecting bracket portion with anarrow seat for an arch wire, said bracket portion having a slot deFinedby a pair of walls for a snap-in entrance to said seat, said wallsdefining a slot narrower than said seat so that they may be forced apartby the wire when a wire is inserted or removed, the horizontal width ofsaid bracket at said slot being substantially greater than the width ofsaid seat.
 2. The orthodontic onlay of claim 1 wherein the width of saidseat is substantially the same as the diameter of the wire.
 3. Theorthodontic onlay of claim 1 having at least one vertical openingthrough said bracket portion for anchoring a control auxiliary.
 4. Theorthodontic onlay of claim 3 having a shelf at the top and bottom ofsaid vertical opening and wings on each side of said bracket forward ofsaid shelf and extending vertically therebeyond and separated from eachother, for tying ligatures thereto.
 5. The orthodontic onlay of claim 1wherein said slot comprises an outer portion having converging surfacesleading to two parallel surfaces that lead into said seat.
 6. Theorthodontic onlay of claim 1 wherein said bracket portion includestapered surfaces that converge toward each side of said seat.
 7. Theorthodontic onlay of claim 6 wherein the surface on each side of saidseat slopes away therefrom in all directions at an angle of about 20*,thereby resulting in imparting a braking force of friction to the archwire when it enters or leaves the seat in either direction at an angleof the same amount.
 8. The orthodontic onlay of claim 1 wherein saidbracket portion diverges laterally from each end of the walls definingsaid slot.
 9. An orthodontic onlay for use with an arch wire in alight-wire technique comprising a plastic member to be directly cementedto a tooth and having a base portion with a rear surface that conformssubstantially to the forward surface of the tooth to which it is to becemented and a bracket portion with a generally circular narrow seat foran arch wire, said bracket portion having a slot defined by a pair ofwalls for a snap-in entrance to said seat, said walls defining a slotnarrower than said seat so that they may be forced apart by the wirewhen a wire is inserted or removed, the horizontal width of said bracketat said slot being substantially greater than the width of said seat.10. The orthodontic onlay of claim 9 wherein the width of said seat issubstantially the same as the diameter of the wire.
 11. The orthodonticonlay of claim 9 having at least one vertical opening through saidbracket portion for anchoring a control auxiliary.
 12. The orthodonticonlay of claim 11 having a shelf at the top and bottom of said verticalopening and wings on each side of said bracket forward of said shelf andextending vertically therebeyond and separated from each other, fortying ligatures thereto.
 13. The orthodontic onlay of claim 9 whereinsaid slot comprises an outer portion having converging surfaces leadingto two parallel surfaces that lead into said circular seat.
 14. Theorthodontic onlay of claim 9 wherein said bracket portion includestapered surfaces that converge toward each side of said seat.
 15. Theorthodontic onlay of claim 14 wherein the surface of each side of saidseat slopes away therefrom in all directions at an angle of about 20*,thereby resulting in imparting a braking force of friction to the archwire when it enters or leaves the seat in either direction at an angleof the same amount.
 16. The orthodontic onlay of claim 9 wherein saidbracket portion diverges laterally from each end of the walls definingsaid slot.
 17. The orthodontic onlay of claim 9 wherein said plastic isclear plastic.
 18. The orthodontic onlay of claim 9 wherein said plasticis tooth color.